Episode Pro giving larger than expected files – cross post

[Ben Wharton]

Attendum:

All the above done on:

Mac Pro 8-Core 2.2gGhz
12Gb RAM
Leopard 10.5.6
QuickTime 7.6
Episode Pro 5.01

[Daniel Low]

Are you sure you are using CBR not VBR?

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Two years from now, spam will be solved. – Bill Gates, World Economic Forum 2004

[Ben Wharton]

Hi Daniel

Thanks for the reply.

Well, I THINK I’m using CBR…

What’s confusing is that under the Flash 8 Bandwidth Setting it has fields for Peak Rate and Average Rate. I’ve set these to BOTH the same value, and then further down in Encoding Settings, I have it set to Use 2-Pass encoding, and 2-pass mode is set to CBR.

Is there something I’m missing?

Ben

[Daniel Low]

Using the bandwidth calc here https://www.digital-rapids.com/layouts/bandwidth_calculator.html the file should be coming out at 810 MegaBytes, a slight difference from your calculation.

If we assume that the rate control of the Flash codec or indeed epsisode is not perfect, and you have to have the file at exactly the size you want then you should compensate by lowering the datarate in episode.

It’s a bit hit and miss but….

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Two years from now, spam will be solved. – Bill Gates, World Economic Forum 2004

[Ben Wharton]

Hi Daniel

Hmmm – for such an expensive piece of software, one that appears to not create CBR files, I’d say either the software was screwy or I’m misunderstanding something about its use / monitoring.

Time to ask telestream direct.

Thanks for the digital rapids link (so glad NOT to be using their systems tho – the software is so poor (but the hardware’s great!))

Ben

[Daniel Low]

[Ben Wharton] “Hmmm – for such an expensive piece of software, one that appears to not create CBR files, I’d say either the software was screwy or I’m misunderstanding something about its use / monitoring.”

Hardly expensive, I use software costing 10x as much and I still cannot rely on exact file sizes at a given datarate for certain codecs.

Remember that ‘Constant’ does not mean ‘Flat’. Flat datarates are only really available with I-Frame only formats. CBR simply means ‘keep a average rate of xxxxKb/s over a certain period of time’, you may find that one of the frames is 1kb and another is 100kb

You’ll find that more capable formats/codecs will maintain far more accurate datarates. Flash is a crap format for video despite its popularity.

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Two years from now, spam will be solved. – Bill Gates, World Economic Forum 2004

[Ben Wharton]

Daniel You know, I just never knew that about Flash not being a constant bit rate in CBR. Do I feel somewhat stupid. Thanks for that little bit of vital knowledge.

But that does work for “all key frame” H264s? I did a short test and it seems to work out, or maybe if it was way longer I’d be proved from again.

You might also be interested that the Digital Rapids calculator is “wrong” – their calculation is based upon a megabyte being 1000Kb, when we all know that away from salemenship, it’s really 1024…

Ben

[Daniel Low]

Flash can contain CBR or VBR video codecs but not Flat rates. You are not stupid, it’s the same for most ‘containers’ eg MOV, MXF, AVI adn so on.

All keyframe is call I-Frame or contrained, where each frame is of a fixed and usually large size adn typically never used for delivery.

Regarding 1000 or 1024, it depends what group you come from: [source wikipedia] but Digital Rapids are right!

1024 bytes: This unit is used when expressing quantities which are based on powers of two, such as memory chip capacities. Most software also expresses storage quantities in units of 1024 bytes. Although the use of “kilobyte” for this unit is common, this usage has been expressly forbidden by the SI standard and other standards organisations. To indicate a quantity of 1024 bytes, the term “kibibyte” (“KiB”) has been recommended instead.

1000 bytes: This definition is recommended for all uses by international standards organizations such as IEC, IEEE, and ISO, with the abbreviation “kB”. This unit is common for quantities which are not based on powers of two, such as bitrates. This term is starting to be adopted by some software, such as the Linux kernel.

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There are no significant bugs in our released software that any significant number of users want fixed. … I’m saying we don’t do a new version to fix bugs. We don’t. Not enough people would buy it. You can take a hundred people using Microsoft Word. Call them up and say “Would you buy a new version because of bugs?” You won’t get a single person to say they’d buy a new version because of bugs. We’d never be able to sell a release on that basis.

Bill Gates. Focus Magazine No. 43 (23 October 1995)